Counter speed limiter



R. E. CROOKE COUNTER SPEED LIMITER Filed Aug. 21. 195 7 25 /6 PA v/vo/v 5 C/P a MW Y/VCHRO/VOI/S ""1 l 3 I 9 Q COUNTER SPEED LIMITER Raymond E. Crooke, Roslyn, N.Y., assignor to Sperry Rand Corporation, Ford Instrument Company Division, Long lsland City, N.Y., a corporation of Delaware Filed Aug. 21, 1957, Ser; No. 679,341

8 Claims. (Cl. 235-91) This invention relates to indicator drive systems and particularly to indicator systems employing high and low speed driving mechanism.

In the present stage of the computer art relating to longitude and/ or latitude high' speed computers efforts to synchronize orreset fine reading counters at high speed due to rapid slewing results in such a high speed of the minutes drums that mechanical failure and breakdown is likely to occur. high speed computers in which the minute drums in present counters would be required to run in the neighborhood of 32,400 rpm.

Accordingly, this invention provides an indicating system in which the degrees and minutes drums of a counting mechanism are actuated in such a manner that the minutes drum will not be driven above a given speed but will be driven in proper relation to the degrees drum below said given speed;

Other advantages and features. of the indicator mechanism may be appreciated on reading the following description in conjunction with the drawings, in which Fig. 1 is an elevation view of the indicator mechanism, and

Fig. 2 is a detail of the centrifugal brake mechanism employed by the indicating mechanism.

The mechanism comprises a degree counter 11, and a separate independently driven minute counter 22 operatively associated therewith.

As shown in Fig. l, a pair of synchronous receivers 3i and 4 control the motor 5 the output of which is placed in gear box 6; the motor output is fed through the gear box 6 back to the receivers and on shaft 7 to a second gear box 3 which has a pair of output shafts 9 and 10. The shaft 9 drives degree counter 11 through the Geneva gears 12 and 13, low speed shaft 14, bevel gears 15 and 16 and counter shaft 17.

The high speed driving means for minute counter 22 includes the shaft 10, gear box 18, output shaft 19, interruptable coupling 20, high speed shaft 21, bevel. gears 23 and 24, and counter shaft 25.

The interruptable coupling comprises a disk 26 which is secured to the upper end of the shaft 19, and a heart shaped disk 28, having a depression 40 in the periphery thereon, which is secured to the lower end of the shaft 21. A lever 27 which is pivotally secured to the disk 26 is provided with a cam follower 41 which is normally yieldingly held in the depression 40 by a tension spring 30 having one end thereof secured to the disk 26 and the other end thereof secured to the lever 27. During normal operation of the mechanism the shaft 21 will be driven in unison with the shaft 19 through the disk 26, lever 27, cam follower 41 and disk 28, due to the engagement of the cam follower 41 with the disk 28 in the depression 40 thereof. But when the shaft 19 is rotated faster than a predetermined rate, due to fast slewing, the cam follower 41 will be thrown out of the depression 40 by centrifugal force thereby breaking the driving connection between the shaft 19 and the shaft 21 and stopping the rotation of the This is especially true of the modern 511$ States Patent shaft 21 which will then remain stationary untilthe cam. follower 41 again engages the depression 40. The speed of the shaft 19 at which the cam follower 41 is thrown out of thedepression 40 is dependent upon the rigidity of the tension spring 30 which in turn is dependent upon the maximum allowable speed of the minute counter 22. The interruptable coupling 20, as described, therefore con.- stitutes in effect a single position centrifugally actuated clutch. The counter 22 will always read the same upon re-engagement ofthe camfollower 41 with the depression 40 as it did at the time of disengagement, regardless of the number of rotations of the shaft 19 between disengagement and re-engagement.

The connection-between the shaft 21 and the counter 22 is'such that the counter 22 is advanced sixty minutes (60) or one degree (1") for each revolution of the shaft 21. Therefore, since the shafts 9 and 19 are both rotating in their timed relation to each other during disengage ment of the shafts 19 and 21, the counter 22 will always be in synchronism with the counter 11' upon re-engagement of the shafts 19 and 21. For example, let it be assumed that the shafts 19 and 21 were disengaged when the counter 22 read 36 and the counter 11 read 104 and that the shaft 19 made ten revolutions between disengagement and re-engagement of the shafts 19 and 21. During this time the counter 22 would not have been registering but the counter 11 would have been advanced ten degrees from 104 to 114, so that upon re-engagement the counters 11 and 22 would read 11436, the correct reading. The same holdsv true for any number of revolutions of the shaft 19 during disengagement thereof with the shaft 21.

Preferably the mechanism is provided with a centrifugal brake 31 shown in plan in Fig. 2. This brake comprises a drum plate having an internal drum face 33 lining a circular aperture in the plate. Centrally disposed within the aperture is a rotating member 34 mounted on the shaft 21. Brake arms 35 and 36 are pivotally attached to the member 34 on each side of the shaft 21, the arms being inwardly biased by springs 37 and 38 which connect the free end of each arm to the pivotal end of the opposing arm. The arms have foot members with curved outer surfaces adapted to bear on the drum face 33 when the arms are outwardly pivoted by the rotating speed of the driven member 34. Accordingly, the brake provides additional protection for the minute counter against excessive speed in the event the interruptable coupling fails to disengage.

It is understood that modifications in the actual design of the indicating mechanism may be effected without departing from the scope of invention as defined in the appended claims.

What is claimed is:

1. An indicating mechanism for visually indicating changes in degrees and minutes of latitude or longitude having a degree counter which is operative to indicate changes in degrees of latitude and/or longitude, and a separate independent minute counter which is operative to indicate changes in minutes of latitude and/or longitude in conjunction with said degree counter, and means by which said degree counter and said minutes counter are adapted to be actuated in accordance with signals imparted to said mechanism, said mechanism comprising; a degree counter which is adapted to be constantly driven, a separate independently driven minutes counter which is adapted to be driven in timed relation to said degree counter when said degree counter is driven below a predetermined speed, and to be maintained stationary when said degree counter is driven above said predetermined speed, a power input shaft which is adapted to be constantly driven at varying speeds in accordance with signals imparted to said mechanism, a first output shaft which is adapted to be constantly driven by said power shaft, a second output shaft which is adapted to be constantly driven by said power shaft independently of said first output shaft and at a substantially greater speed than said first output shaft and in a constant predetermined ratio with respect to said first output shaft, interconnecting means between said first output shaft and said degree counter through which said degree counter is adapted to be driven by said first output shaft, a high speed connecting shaftdisposed in axial alignment with said second output shaft with the upper end thereof operatively connected to, said minute counter, and a centrifugally actuated single position clutch means interposed between said high speed connecting shaft and said second output shaft through which said connecting shaft is adapted to be driven in unison with said second output shaft below a predetermined speed of said second output shaft and by which said connecting shaft is adapted to be automatically disconnected from said second output shaft when said second output shaft exceeds said predetermined speed.

2. An indicating mechanism as defined by claim 1 in which said clutch means comprises a first disk secured to the lower end of said high speed connecting shaft, a depression in the periphery of said first disk, a second disk secured to the upper end of said second output shaft in close proximity to said first disk, an arm pivotally secured to said second disk, a cam follower secured to the free end of said arm for engagement in the said depression in said first disk, a tension spring yieldingly biasing said cam follower into engagement with said depression, said cam follower being adapted to be thrown out of engagement with said depression when said second output shaft exceeds said predetermined speed.

3. An indicating mechanism as defined by claim 2 in which said high speed connecting shaft is provided with a. centrifugaily acting brake mechanism.

' 4. An indicating mechanism as defined by claim 3 in which said interconnecting means between said first output shaft and said degree counter includes means by which said degree counter is intermittently driven by said constantly driven first output shaft.

5. An indicating mechanism as defined by claim 4 in which said means by which degree counter is intermittently driven by said constantly rotating first output shaft comprises a low speed connecting shaft and a geneva drive through which said low speed connecting shaft is adapted to be driven by said first output shaft.

6. An indicating mechanism as defined by claim 1 in which said high speed connecting shaft is provided with a centrifugally acting brake mechanism.

7. An indicating mechanism, as defined by claim 1 in which said interconnecting means between said first output shaft and said degree counter includes means by which said degree counter is intermittently driven by said constantly driven first output shaft.

8. An indicating mechanism'as defined by claim 7 in which said means by which said degree counter is intermittently driven by said constantly rotating first output shaft comprises a low speed connecting shaft and a geneva drive through which said low speed connecting shaft is adapted to be driven by said first output shaft.

References Cited in the file of this patent UNITED STATESPATENTS 1 1,469,932 Adams Oct. 9, 1923 2,364,980 Jimerson Dec. 12, 1944 2,414,944 Grimshaw Jan. 28, 1947 2,682,373 Opocensky et a1 June 29, 1954 .1 2,722,379 Hayek Nov. 1, 1955 2,746,318 Benjamin May 22, 1956 2,809,291 Nash Oct. 8, 19 57 FOREIGN PATENTS 442,713 Great Britain Feb. 13, 1936 

